This program represents a multidiscipline approach to the study of the reproductive endocrinology of the time period of the ovulation cycle through implantation. The hypothalamo-pituitary-ovarian axis and uterus during the ovulation cycle through implantation will be examined by a group of three Principal Investigators and three co-investigators to determine the regulation of secretion, metabolism, distribution and mechanism of action of hormones that control reproduction. This will be done by in vivo studies, in situ experiments and in vitro incubation, using biochemical techniques for steroid, putative neurotransmitter and protein isolation and synthesis, subcellular fractionations, ligand-receptor interactions, radioimmunoassays, histological autoradiography and ultrastructural analysis, blood flow measurements and isolated hypothalamic preparations.